Abstract: This paper describes the key point of gas-oil valve in daily care and maintenance, including the basic structure, operating procedure, cleaning of filter and replacement, inspection of air-tube and test tube, inspection of hydraulic oil of gas-liquid and oil-level, inspection of voltage of battery, also the problems to be focused on in winter operation. The paper lists following common failures of the gas-oil valve, including abnormal "off" under the condition of normal pressure, failure of Lineguard communication function, air leakage at the junction of air-tube and test tube, unable "fine off" and out of sync signal between field signal and remote signal and. The trouble-shooting methods are given.